The present invention relates to a surge arrester using non-linear resistor made mainly of zinc oxide and more particularly a surge arrester having a bypass gap for shorting a part of the resistor.
An excellent non-linearity of the zinc oxide resistor realized the surge arresters without serially connected discharge gaps. However, for the surge arresters in which the protection level is required to be sufficiently low with respect to the continuous operating voltage of the surge arrester, the non-linearity characteristic of the zinc oxide resistor is not enough. For this reason it is the conventional practice to permit a discharge to occur in the discharge gap connected in parallel with the non-linear resistor block during the surge absorbing operation of the surge arrester so as to shortcircuit a part of the resistor and thereby lower the protection level.
The inventors of this invention have found that in this kind of surge arrester there is a possibility of an overvoltage occurring in the bypass gap leading to the restriking of arc.